Structure & Physical Properties of Carboxylic Acids

Similar to the structure of aldehydes and ketones, the carboxyl carbon atom is sp² hybridised. Thus, the three atoms attached to the carbon lie in the same plane with an approximate bond angle of 120º between them.

Hydrogen Bonding

Carboxylic acids form hydrogen bonds because of the presence of polar carbonyl and hydroxyl groups. Most carboxylic acids exist in dimeric form in which two carboxylic acid molecules are held together by two hydrogen bonds.

Melting and Boiling Point

Intermolecular hydrogen bonding is responsible for high melting and boiling points of carboxylic acids.